This invention relates generally to a device for installing and retaining a sound baffle within a heat tube of a combustion driven heating apparatus.
More particularly the present invention is a retention clip for installing and retaining a sound attenuating insert which is the subject of commonly assigned, co-pending U.S. patent application Ser. No. 08/783,559 filed Oct. 28, 1996. The disclosure of that application is hereby incorporated by reference.
Resonant sound produced by combustion driven heating apparatus is an onerous problem that produces objectionable noise levels. In a conventional combustion driven heating apparatus a fuel is ignited within a burner to produce a flame and hot gases. The hot gases, products of the combustion process, are introduced into a heat exchanger, or heat tube, and then exhausted through a flue stack to the atmosphere. Fluid to be heated, typically referred to as conditioned air, is passed over the outside of the heat tube whereby heat is transferred from the gases inside the heat tube to the exterior of the heat tube and finally to the fluid. The energy imparted to the heat tube by the burner, given certain physical characteristics of the heat tube, sometimes causes the combustion system to oscillate in phase with the natural frequency of the heat tube. This oscillation produces a standing acoustic wave within the heat tube which in turn produces the resonant sounds which are objectionable to humans. It is therefor important to dissipate the energy associated with the standing acoustic wave and thereby reduce the resonance type noise emission of the heating system. The installation of an energy dissipative device, or baffle, in the heat tube is one advantageous approach of dissipating this type of energy.
It is advantageous for system performance that the heat tube remain free from restriction to allow the gases to easily pass through the tube and out the flue stack. Any design that seeks to eliminate or suppress the resonant tones generated in such a system must keep the restriction of the heat tube to a minimum. The build up of combustion byproducts in the form of soot will likewise cause restrictions in the heat tubes that lead to system performance losses. It is typical in the operation of a combustion driven heating system that the heat tubes are frequently cleaned to prevent soot from building up on the heat tubes.
In an effort to eliminate resonant tones in a combustion driven heating system it is also important to prevent leakage of the gases from the heat tubes to the conditioned air. Leakage from the heat tubes to the conditioned air could introduce unreasonably high levels of undesirable gases to areas occupied by living beings. Any attempt to introduce a sound suppression device should therefore be done without piercing the heat tube or otherwise sacrificing the integrity of the seal between the gases and the conditioned air.